I had an 07 M35 (same generation) and it had about 100,000 miles at the time it was totaled by a drunk driver. Only repairs were a battery, a starter, and tires. If you keep up with maintenance, these things will continue to run perfect.
First ... It is unusual for an Infiniti dealership to have a car with this age and mileage on it's lot. They would usually send these to auction. The fact that they did NOT do that speaks to the quality and condition of this car. It is no trouble at all for them to plug into the car and see all codes, all problem areas, etc. If they still wanted to keep it on their lot, it MUST be in sound condition. The 06-07 model years have had a great reliability history, and this car is definitely a good buy (even if priced above book value).
Only three things to do now:
1) Update the NAV disc in the glove box.
http://infiniti.navigation.com/home/en_ ... uItem=Home
2) Find out if any fluids (coolant, gear box, differential) have been changed recently. if not, do that soon as you can.
3) Add one can of Seafoam in a full tank of fuel to clean out injectors.
I say ....... BUY IT!
Just keep in mind that although it appears to be in brilliant shape, with this age there will be repairs in the next few years and repairs aren't cheap on any car.